1. Field of the Invention
This invention relates to a slinger that is secured to the upper end of a submersible motor shaft adjacent a motor bearing. The slinger is operable to propel sand and other particulate contaminants away from the bearing and toward a cooperating outlet communicating with areas external of the motor.
2. Description of the Prior Art
Deep well submersible pumps must operate reliably for extended periods within a somewhat hostile environment. Oftentimes, wells are drilled into subsurface layers of the earth having a large percentage of sand or other potentially mobile, grit-like contaminants that are transported toward the pump during operation of the latter. However, the use of a filter having effective openings small enough to prevent entry of relatively small particulate material into the pump is generally considered unsatisfactory, due to the difficulty of lifting the pump assembly out of the well for periodic filter replacement. Consequently, it has become common practice to allow such contaminants to enter the pump along with the water so that a filter downstream of the pump and ahead of the point of use can be disposed at a more convenient and accessible location.
As a result, it is desirable to construct submersible pumps to withstand any adverse effects of the flow of sand and other abrasive, grit-like contaminants through the pump assembly. Sand, for example, can quickly damage a relatively soft sleeve bearing supporting the motor armature to the point where the useful life of the motor is significantly reduced. However, the use of an ordinary shaft seal surrounding the shaft and connected to a motor end member cannot, by itself, effectively preclude entry of such contaminants into the area adjacent the bearing.
In the past, certain submersible pumps have been provided with a rubber body or slinger which surrounds the motor shaft above the shaft bearing and shaft seal. The slinger is typically positioned within a lowermost portion of a chamber defined by structure interconnecting the motor and pump stages, wherein the structure has an inlet opening for enabling passage of water from the well, into the chamber and toward the first or lowermost impeller. Known prior art slingers typically have a cylindrical, conical, or convex outer surface which is generally smooth, so that during rotation of the shaft, the outer surface of the slinger agitates the water in the adjacent areas in an effort to prevent sediment in the water from settling toward the underlying seal and bearing.
Unfortunately, operation of such slingers over the years has proved to be somewhat unsuccessful in effectively directing the contaminants away from the bearing. Although the smooth rotating surface of these slingers agitates the surrounding water, denser particles are often unaffected by the agitation and instead settle toward the bottom of the chamber. In these instances, the slingers often function in a manner similar to an umbrella and merely shield the bearing from the settling contaminants.
Moreover, the chambers of prior art pumps often are provided with an inlet spaced some distance above the slinger, so that the slinger is located in a relatively "dead" area away from the flow of water between the well and the first pump stage. As a result, some particles remain in the lowermost portion of the chamber unless flushed out by water draining back in reverse direction through the pump when operation of the latter is interrupted. In wells with relatively large amounts of particulate contaminants, buildup of the contaminants can occur in a relatively short period of time to the point where the pump is literally "choked" and unable to run.